Process of manufacturing lactic acid.



'WILHELM KLAPPROTH, 0F NIlEDER-INGELHEIM-DN-THE-RHINE,. GERMANY.

No Drawing.

1 rnoonss or MANUFACTURING LACTIC ACID.'

Specification of Letters Patent. Patented Jan. 18, 1910.

Application filed April 1, 1909. Serial No. 487,251.

To all whom it may concern:

Be it known that I, WILHELM ITLAPPROTH, a subject of the'Emperor of Germany, re-

siding at- Nieder-Ingelheim-on-the-Rhine,

Germany, have invented certain new and useful Improvements in a Process of Manufacturing Lactic Acid from Lactate of Lime, of which the following is a specification.

According to the method hitherto employed for obtaining lactic acid from lactate of lime sulfuric acid is added direct to the dilute solution of this salt such as results from the fermentation process, and the lactic acid obtained by filtration, having a strength of about 10 per cent., is further concentrated by evaporation and purified. This'method has the disadvantage that an acid solution has to be dealt with, thus causing great difficulties with regard to the apparatus. Besides,- in evaporating solutions containing free lactic acid considerable quantities of the latter are lost. Ithas been attempted, in practice, to overcome these difficulties by concentrating the solutions before decomposition, so that the solutions which are boiled down contain chiefly lactate of lime. But this method has another drawback, in that it is difficult to work up almost solid paste of sulfate of lime. is

formed on the addition of,sulfuric acid, not admitting of any further working up. The inventor has found-by careful experiments that these difliculties may be overcome by effecting the decomposition of the solutions containing lactate of lime in the presence of concentrated lacticacid, said solutions being previously concentrated, if necessary, as before. It has been found, that, according to the quantity of concentrated acid present a more or less thin, nota firm, solid magma is obtained which may be filtered without dilficultv. In thismanner lactic acid may be obtained direct in a salable degree of con-.

centration. 7

As, according to this new process, not an acid but a neutral solution has to be boiled down, it is self-evident that there is no difficulty as to apparatus and that the losses inherent in the evaporation of free lactic acid are avoided. It has-further been found that in this way an acid more free from anhydrid is obtained than with the old the said salt.

process of evaporating dilute acid. This is all themore surprising as in reality an expert would perhaps expect that the addition of concentrated sulfuric acid to the hot liquid would cause 'an increased formation of-anhydrid, z'. e. a combining of two molecules of lactic acid by elimination of water.

The concentrated a ctic acid may either.

be added to the concentrated calcium lactate solutions before decomposition or it may be added to the acid used for decomposition of The solution of lactate of lime may also be evaporated to dr ness and stirred, in the powdered form, rst' with lactic acid preferablyheated. to about 50 C. and then with a suitable acid such as sul' furic, hydrofluoric, or oxalic acid, or the lactic acid may be added first to the acid to be used for decomposition and the dry lactate then stirred with this mixture, after which the lactic acid is separated in any suitable manner.

The following ris an example of how, the

recess maybe carried out in detail: 200

lters of a solution of lactate of lime coming from the fermenting process and having a strength of 10 Baun are boiled down to 50 liters and in this state or after purificaable agent, such as animal charcoal, and filtration, 50 kilograms of a 50 per cent. lactic 'tion by a suitable process forcxample, by decolorizing the lactate solution by a suitacid are added. Decom ositlon is then effected means of Sn] uric acid, and the. lactic acid separated from the calcium; sulseparating the lactic acid.

2. The process of manufacturing lactic acid from solutions containing lactate of lime which consists in concentrating these solutions, by evaporating to dryness, recipitating the lime of the concentrated actate by an acid in thepresence of added concentrated free lactic acid and separating the lactimac'id.

3. The process of manufacturing lactic In testimony whereof I have hereunto set acid from solutions containing lactate of my hand in presence of two subscribing Witlime which consists in concentrating these nesses.

solutions, precipitating the lime of the con- VVILHELM KLAPPROTH. 5 centrated lactate by an acid mixture which Witnesses:

contains concentrated free lactic acid and JEAN GRUND,

separating thelactic acid. CARL GRUND. 

